Study on Extrusion Process and Properties of Wood Plastic Composites

Wood plastic is a new type of modified environmental protection produced by using waste plastic instead of commonly used resin adhesives, and plant fibers such as wood flour, rice husks, and agricultural straws as raw materials. 

As an important branch in the field of composite materials, WPC related research is highly valued, including several aspects, such as: physical and mechanical properties of WPC, interface compatibility between wood and plastic, and manufacturing process control.

WPC extrusion technology

Extrusion molding, also known as extrusion molding or extrusion molding, is a type of molding that uses heat from the screw to force heated molten plastic to pass through a die and force it into a continuous profile with a constant cross section under the pressure of a pressure. method.

Extrusion can mold almost all thermoplastics. The products produced are pipes, plates, cable coverings, and composite materials of plastics and other materials. It is a molding method with high production efficiency, wide use and strong adaptability. When used to produce wood-plastic composite materials, the WPC extrusion line has the advantages of stable product quality, lower cost, and relatively small investment.

The main equipment for the production of wood-plastic composites by extrusion is screw extruders, including single screw extruders, parallel twin screw extruders and conical twin screw extruders.

Performance comparison of different resin-based wood-plastic composites

Because the maximum processing temperature of wood fiber fillers used in wood-plastic composites is generally 200 ° C, wood-plastic composites generally use thermoplastic resins such as PE, PP, and PVC with relatively low processing temperatures. The matrix resins are different. The performance varies greatly.

The stiffness and tensile strength of PE are small. Compared with other polymers, PE has excellent properties of flex resistance, water resistance, chemical resistance and low temperature flexibility, good processability and low price. Among them, HDPE has higher tensile strength, surface hardness, and stiffness than LDPE. As people's living standards continue to improve, people's requirements for the properties and texture of wood-plastic composites are also increasing. Therefore, HDPE resins are currently used as the matrix. Wood-plastic composites account for most of them and are generally used for outdoor components.

PP melt has low viscosity, low temperature sensitivity and good processability. Compared with HDPE, it has higher tensile strength, surface hardness, tensile yield strength and stiffness, but it is brittle at low temperatures. The weather resistance of PP-based wood-plastic composites is not as good as that of PE-based wood-plastic products, which limits its application scope to a certain extent.

PVC has the advantages of high rigidity, high strength, and low price. It has good adhesion, but it has poor cold resistance, aging resistance, thermal stability, and poor processability. These disadvantages can be improved by adding additives. PVC has high melt strength and can be used to prepare wood-plastic foam composites, currently. PVC-based wood-plastic composite materials are mainly used in interior decoration materials.

At present, people pay more and more attention to ecological problems and resource crises. Therefore, people have also set off a new wave of research on WPC extrusion machines. After the emergence of wood-plastic composite materials, natural resources have been fully utilized, reducing the environmental pollution caused by waste plastics and waste furniture and waste wood products. Although China started relatively late in this respect, it is developing very fast and industrialized production and processing technologies are gradually becoming mature.